dos prompt, types of commands .27 t028

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DOS-Prompt, Types of commands


Objective

On completion of this period, you would be able On completion of this period, you would be able to knowto know

DOS , Terminology usedDOS , Terminology used

Types of commands Types of commands


Recap

In the previous class, we have learnt about

How many types of operating systems are there ?

Single User Operating Systems

Multi User Operating Systems


Prerequisite

DOS stands for Disk Operating System


Disk Operating System

The MS-DOS version that was released with IBM-PC’s was known as version 1.0

The memory occupied by it was as low as 12K

It supported 5(1/2) –inch diskette with 160K of capacity

MS-DOS version 1.0 had about 4000 lines of code


Disk Operating System (contd)

This system consisted of three basic programs

IBMBIO.COM for disk and character I/O system

IBMDOS.COM for disk and file management

COMMAND.COM for interpreting commands



MS-DOS used the ROM of IBM PC called BIOS (Basic Input Output System) that contained drivers for various standard devices

This version supported only one single directory



This system has to handle batch files

Later version 1.1 came. After then 2.0 of MS-DOS that is totally a new operating system

Later version 3.0, 4.0, 5.0, 6.0 etc. have come with more and more advanced features and added utilities



Two other programs in MS-DOS are

CONFIG.SYS for system configuration

AUTOEXEC.BAT


Terminology Used

ProgramA finite set of sequence of instructions

These instructions are used to make the computer know the task to be performed


Terminology Used (contd)

FileFile is a collection of text or data that are

logically relatedThese are quite similar to the manual files

that we maintain to hold mails, memos etc

File name consists of two parts File NameFile Extension



File name can be upto 8 characters long

Characters can be either in upper or lower case letters, digits, and underscore

File extension is used to identify the file type



MS-DOS permits three character extensions

Some of the commonly used extensions are .exe, .bat, .txt, .dat, .com etc.,

MS-DOS converts the file names to uppercase automatically


Terminology Used (contd)MS-DOS supports the following files1. Text Files

These are the files used to store data

The data can be in the form of characters, numbers and any other symbols

These are the files used to store input as well as output data of the programs



2. Batch FilesThese contain a set of executable

instructions that are to be executed as a Batch in a sequential order

3. Application Files These are usually application specific.They are used to perform specific tasks

that will enable a user to do his job easily.



Word processors, spreadsheets, Data Base Management System etc., are some application program files

4. Directory

To store all the related files at one place so that our search for a specific file becomes easier



Directory is a logical grouping of files

A directory contains the names of the files it holds, along with their extension, the file size, the date of creation or the date of last modification


Structure of MS-DOS Disk

MS-DOS divides the disk into two parts so that the disk is organized effectively

These two parts of the disk are

1. System area

2. Data area


System area

It is the area of the disk which is used by the MS-DOS operating system to keep the track of any vital information about the disk

This system area uses very small portion of the disk , which is about 2% of total capacity


System Area (contd)

This system area is further divided into

1. Boot area

2. Fat area

3. Root directory


Boot Area

The boot area, also known as boot record is the first part of a DOS disk

This area stores a program, which is used to do the task of beginning and loading the MS-DOS operating system into the memory of the computer

This process is known as Booting process


Boot Area (contd)

The booting process can be of two types

Cold Boot – switching the power of computer system enables the computer to start up

Warm Boot – restarting a computer when it hangs up


FAT Area

FAT stands for File Allocation Table

It is the next part of the system area of the disk

This area of FAT is used by the MS-DOS to manage the big data portion of the disk


FAT Area (contd)

This area is used to record the status of each area of the disk

For managing the area of the disk, the MS-DOS operating system divides the total area into logical divisions known as clusters


Root Directory

This is the last part of the system area of the disk

This the file directory, which is the basic , but in directory for the disk, which every disk has

The directory records the files that are stored on the disk

This directory has a fixed size for each disk format


DATA Area

It is bigger part of the disk, where the data files are stored on the disk

Each file on the disk has an entry in the FAT table of the system area

Once a file in the data area is assigned a cluster it finds the entry into the FAT table

The data nearly forms 98% of the disk capacity


System Prompt (Command Prompt)

A system prompt is an indication that the system is ready to take input or instructions from the user and give appropriate output to the user

From the prompt we give the instruction to the computer


System Prompt (Command Prompt) (contd)

For MS-DOS. If we are using a hard disk computer, the DOS is fetched into the memory of the computer from the hard disk

DOS assumes the default disk drive ‘C’, so it gives an initial system prompt as C:\>


MS-DOS Commands

The instructions which are used to communicate with the computer system

We call these instructions as commands and we

issue commands to the system to get our work done


MS-DOS Commands (contd)

The commands of DOS are divided into two categories

Internal Commands

External Commands


Internal Commands

Internal commands are built–in commands

These commands are in COMMAND.COM program

This program is loaded with the operating system into the memory during the booting


Commands Examples

Internal commands – COPY, DEL, DIR, TYPE, CD, MD, RD, MODE, PATH, DATE,TIME, COPY CON etc

External commands – FORMAT, CHKDSK, SCANDISK, XCOPY, ATTRIB, DISKCOPY, PRINT, TREE, DELTREE etc


Summary

In this class, we have learnt about

DOS , Terminology usedDOS , Terminology used

Types of commandsTypes of commands


Frequently Asked Questions Expand MS-DOS. List the programs that

constitute MS-DOS

List any four internal and external commands


Quiz

1. The last part of the system area of the diska. FAT areab. Boot areac. Root directory.

Answer: c


Quiz

2. Which file contains a set of instructions that are to be executed as a Batch in a sequential ordera. text filesb. Batch filesc. application files

Answer: b

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dos prompt, types of commands .27 t028

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